The number of migrant parents entering the United States with children has surged to record levels in the three months since President Trump ended family separations at the border, dealing the administration a deepening crisis three weeks before the midterm elections.

Border Patrol agents arrested 16,658 family members in September, the highest one-month total on record and an 80 percent increase from July, according to unpublished Department of Homeland Security statistics obtained by The Washington Post.

Large groups of 100 or more Central American parents and children have been crossing the Rio Grande and the deserts of Arizona to turn themselves in, and after citing a fear of return, the families are typically assigned a court date and released from custody.

“We’re getting hammered daily,” said one Border Patrol agent in South Texas who spoke on the condition of anonymity because he was not authorized to speak to the news media.

Having campaigned on a promise to stop illegal immigration and build a border wall, Trump now faces a spiraling enforcement challenge with no ready solutions. The soaring arrest numbers — and a new caravan of Central American migrants heading north — have left him in a furious state, White House aides say.

Trump has been receiving regular updates on the border numbers, telling senior policy adviser Stephen Miller and Chief of Staff John F. Kelly that something has to change, according to senior administration officials.

Aides including Miller and White House press secretary Sarah Huckabee Sanders have continually told the president that many of the children coming across the border are being smuggled illegally and that the United States is being taken advantage of. The president’s welling anger has left him pushing once more for a reinstatement of a family-separation policy in some form, which he believes is the only thing that has worked, despite the controversy it triggered.

One senior official, also not authorized to speak to the media, conceded that the separations were halted to stanch political fury but ended up sending a “clear signal” that people could cross, adding, “Now we’re actually getting crushed.”

GOP strategists working on the midterms said that the separations coincided with the worst polling times of the presidency and that reinstituting separations would sag numbers for the Republicans, who are already struggling in many close races.

Trump continues to criticize Homeland Security Secretary Kirstjen Nielsen and has asked Secretary of State Mike Pompeo to work with Mexico to make it tougher for Central American immigrants to cross its southern border, inserting the issue into ongoing trade negotiations.

A senior DHS official said Wednesday that Nielsen continues to take the lead role engaging with leaders from Central America on migration issues and has been in regular contact with the Mexican government and the transition team of President-elect Andrés Manuel López Obrador, who will take office Dec. 1.

Trump has been lashing out this week at the new caravan of 2,000 migrants, mostly from Honduras, who crossed into Guatemala on Monday, pushing past police roadblocks. On Tuesday, Trump threatened to cut off aid to Guatemala, Honduras and El Salvador if their governments “allow their citizens, or others, to journey through their borders and up to the United States.”

In a tweet Wednesday morning, Trump urged GOP candidates to campaign on the issue. “Hard to believe that with thousands of people from South of the Border, walking unimpeded toward our country in the form of large Caravans, that the Democrats won’t approve legislation that will allow laws for the protection of our country,” he wrote. “Great Midterm issue for Republicans!”

The latest DHS figures show 107,212 members of “family units” were taken into custody during fiscal 2018, obliterating the previous high of 77,857 set in 2016.

The number of “unaccompanied alien children” and single adults apprehended remained essentially unchanged last month, another indication that more migrants who might have traveled alone in the past are now bringing children with them.

Katie Waldman, a DHS spokeswoman, said the agency did not have official numbers ready to publish, but “current trends indicate enforcement efforts against single adults entering illegally have been hugely successful.” However, she said, “the removal of actual family units, or those posing as family units, has been made virtually impossible by Congressional inaction — which will most likely result in record numbers of families arriving illegally in the United States this year.”

There have been several senior-level meetings at the White House about the numbers, administration officials say, at which Miller has channeled the president’s frustration.

Miller is pushing for a more aggressive stance, including changes at U.S. ports of entry that would make it tougher for asylum-seeking Central Americans to gain admission.

Another option under consideration, known as “binary choice,” would detain migrant families together and give parents a choice — stay in immigration jail with their child for months or years as their asylum case proceeds, or allow their child to be assigned to a government shelter while a relative or guardian can apply to gain custody.

Some DHS officials remain wary of the proposal and the potential blowback it could bring, and there is a lack of detention space to accommodate the record wave of parents and children coming across.Immigration and Customs Enforcement has about 3,300 detention beds at three “family residential centers,” but five times as many parents and children are crossing each month. The volume has overwhelmed Border Patrol stations and prompted mass releases.

Though the Rio Grande Valley of South Texas remains the busiest corridor for illegal crossings, Border Patrol agents in recent weeks have seen a new increase in southern Arizona. Bus-loads of migrant parents and children have been dropped off at churches and charities there by ICE, which has little detention space for families and pregnant women.

The latest DHS figures show U.S. agents made 396,579 arrests along the Mexico border during the government’s 2018 fiscal year, a 30 percent increase over the same period in 2017, when illegal migration dropped to a 56-year low.

Trump viewed the 2017 figures as a validation of his tough rhetoric on illegal immigration and had plans to campaign on the achievement this year. When border arrests jumped earlier this spring, he berated Nielsen and demanded swift action, furious to be losing ground on one of his core issues.

That led to the “zero tolerance” prosecution initiative this spring and the separation of at least 2,500 children from their parents, hundreds of whom were deported without their sons and daughters. The president issued an executive order June 20 ending the practice amid public outcry.

DHS officials have seen a particularly large increase this year in families arriving from Guatemala, where smuggling guides have been encouraging migrants to bring children with them to avoid deportation.

Courts have limited the amount of time minors can be held in immigration jails to 20 days, so many parents who arrive with children are fitted with ankle monitoring bracelets and given a court appointment that may be several months away.

Administration officials blame this “catch and release” model for the growing number of families arriving at the border, proposing to end it by expanding family detention space and changing rules that limit their ability to hold children in long-term custody.

Agents along the border say the family migration surge has continued this month.

“If October is any indication of what’s to come, Fiscal Year 2019 is going to be a very busy year,” Manuel Padilla Jr., chief of the Border Patrol’s Rio Grande Valley sector in South Texas, said on Twitter. Agents in the sector, the busiest for illegal crossings, arrested more than 1,900 people last weekend alone, according to Padilla.